Tetracycline hydrochloride is a widely used antibiotic for treating bacterial infections, but its misuse poses serious health risks. Therefore, it is crucial to accurately detect tetracycline in complex matrices. In this study, we propose a simple, enzyme-free absorbance biosensor for tetracycline detection based on the optical properties of chitosan-capped ZnS doped with Mn nanomaterials. The biosensor can detect tetracycline in a range from 13.1 pM to 72.2 pM, with the best detection limit being 2.13 pM in deionized water. It can also differentiate tetracycline from ampicillin, penicillin, cephalexin, amoxicillin, and glucose within the aforementioned range. Moreover, this novel sensor has proven reliable over time, and its performance has been demonstrated in tap water and milk. The results have the potential to revolutionize antibiotic monitoring in clinical and environmental settings, thus contributing to the global fight against antibiotic resistance.
